Tobacco smoking is considered a major public health challenge, responsible for more than 400,000 deaths each year in the United States alone. To reduce the risk of health damage caused by tobacco smoke (TS) the tobacco industry is marketing and advertising a line of reduced-exposure tobacco products (such as Advance manufactured by Brown & Williamson Tobacco Corporation, Omni and Quest 3 manufactured by Vector Group Ltd), which claim to be less harmful than the leading light cigarette brands. However, the scientific evidence provided is insufficient to evaluate whether these products actually reduce the users' risk for tobacco-related diseases including those associated to vascular impairments. Despite the strong evidence for an association between tobacco smoke and vascular impairment, the impact of TS exposure on the blood-brain barrier (BBB) has been only marginally addressed and studies were limited to only few selective substances among the thousands contained in TS thus, leaving BBB research a substantial understudied area. To address these relevant health public concerns we propose a multimodal approach that involve the parallel use of 1) a novel humanized dynamic in vitro BBB model; 2) freshly isolated peripheral blood immune cells (PBMC) and platelets from smoker and non-smoker volunteers; 3) 3 vessel occlusion rat models of focal ischemia that will be used to complement the results in vitro and assess the likelihood and magnitude of secondary brain injury (brain edema) caused by TS exposure (from regular and reduced-exposure) in synergism with temporary loss of blood flow. Based on these premises we propose to: 1. Evaluate the effect of tobacco smoke from reduced-exposure and regular tobacco products on BBB integrity and function and assess the immunoactivity of each tobacco product. 2. Investigate the effect of TS exposure on BBB function and viability in synergism with rheological changes and how this may impact the pathogenesis of secondary brain injury.